The parenteral administration of medical liquids is an established clinical practice. The liquids are administered particularly intravenously, and the practice is used extensively as an integral part of the daily treatment of medical and surgical patients The liquids commonly administered include blood and blood substitutes, dextrose solution, electrolyte solution and saline. Generally the liquids are administered from an intravenous delivery system having a container suspended above the patient, with the liquid flowing through a catheter hypodermic needle set to the patient.
The administration of liquids intravenously is a valuable and important component that contributes to the optimal care of the patient; however, it does not provide a satisfactory means and method for administering concomitantly therewith a beneficial agent. Presently a beneficial agent is administered intravenously by (2) temporarily removing the intravenous system administering the agent to the patient followed by reinserting the intravenous system into the patient; (2) an agent is added to the liquid in the container and then carried by the flow of the liquid to the patient; (3) agent is added to a liquid in a separate container called a "partial fill" that is connected to the primary intravenous line through which line the agent is carried by the flow of liquid to the patient; (4) agent is contained in a piggyback vial into which is introduced an intravenous fluid, with the vial subsequently connected to the primary line through which the agent is administered to a patient, or, (5) agent is administered by a pump that exerts a force on a liquid containing agent for intravenously administering the liquid containing the agent. While these techniques are used, they have major disadvantages. For example, they often require preformulation of the agent medication by the hospital pharmacist or nurse, the require separate connections for joining the primary intravenous line that further complicates intravenous administration, the use of pumps can produce pressures that can vary at the delivery site and the pressure can give rise to thrombosis, and the rate of agent delivery to the patient often is unknown as it is not rate-controlled agent delivery, but delivery dependent on the flow of fluid administered over time. In view of this presentation it is apparent a critical need exists in the field of intravenous delivery for a rate-controlled means for administering a beneficial agent in intravenous delivery systems.